The Oxidation of the Endogenous Cannabinoid Anandamide and the Synthetic Cannabinoid JWH-018, a Drug of Abuse, by Human Cytochrome P450 2J2.

Abstract

Cytochrome P450s (CYPs) are a superfamily of monooxygenases catalyzing the metabolism of various endogenous and exogenous compounds. CYP2J2 is highly expressed in the cardiovascular system and catalyzes the metabolism of arachidonic acid to give four vasoactive epoxyeicosatrienoic acids (EETs). Similar to the endogenous cannabinoid system, CYP2J2 is also expressed in the gastrointestinal tract, liver, kidney, and the brain. Therefore, we investigated the ability of CYP2J2 to metabolize anandamide (AEA), an endogenous cannabinoid, and JWH-018, a synthetic cannabinoid, thereby contributing to the regulation of the ECS. We determined that purified CYP2J2 metabolizes AEA to give the 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acid-ethanolamides (EET-EAs) and 20-hydroxyeicosatrienoic acid-ethanolamide (HETE-EA) and characterized the metabolism in detail. Since AEA plays a role in energy balance, we investigated AEA metabolism by rat liver microsomes from rats bred to be susceptible or resistant to diet-induced obesity and determined that both diet and obesity have significant effects on AEA metabolism. Approaches for increasing the stability of the EET-EAs may aid in understanding their biological actions in vivo. Therefore, we tested several inhibitors of soluble epoxide hydrolase (sEH), the enzyme primarily responsible for EET hydrolysis, as inhibitors of the hydrolysis of EET-EAs. Our results indicate that the compounds tested were not efficacious and that new inhibitors specific for the EET-EAs’ epoxide hydrolases need to be developed. Finally, we determined that JWH-018 is a substrate for CYP2J2 and characterized its metabolism in detail. JWH-018 is a drug of abuse that causes several adverse cardiovascular side effects, but relatively little is known about the metabolism or the pharmacology of this compound. Utilizing an animal model, we determined that JWH-018 causes a significant increase in blood pressure that appears to be only partially mediated by activation of the cannabinoid 1 receptor. Additional studies are required to fully understand the involvement of CYP2J2 in the ECS; however, because CYP2J2 regulates the metabolic fates of at least two ligands for the ECS, it is possible that CYP2J2 may play an important role in the ECS.